Pilar Cyst


Article Author:
Daifallah Al Aboud


Article Editor:
Bhupendra Patel


Editors In Chief:
Amanda Oakley
Jules Lipoff
Shyam Verma


Managing Editors:
Orawan Chaigasame
Carrie Smith
Abdul Waheed
Frank Smeeks
Kristina Soman-Faulkner
Benjamin Eovaldi
Radia Jamil
Sobhan Daneshfar
Saad Nazir
William Gossman
Pritesh Sheth
Hassam Zulfiqar
Steve Bhimji
John Shell
Matthew Varacallo
Ahmad Malik
Mark Pellegrini
James Hughes
Beata Beatty
Hajira Basit
Phillip Hynes


Updated:
3/24/2019 8:35:08 PM

Introduction

Pilar or Trichilemmal cysts are common dermal cysts. They occur in less than 10% of the population. Of all skin cysts, Pilar cysts are the most common cysts, mostly affect the skin of the scalp. Trichilemmal cysts never give rise to malignant lesions. They are usually sporadic. The cysts contain keratin and are outlined by stratified squamous epithelium similar to what we see in the outer(external) root sheath of the hair follicle. Proliferating trichilemmal cysts are the tumor form of pilar cysts, and it would appear in less than 3% of all cases of pilar cysts, and it might ulcerate and may be locally aggressive.

Etiology

Trichilemmal cysts may be inherited as an autosomal dominant trait. Patients with familial pilar cysts are often younger and often present with multiple lesions at the same time. They arise from the epithelium located between the sebaceous gland and the arrector pili muscle. They are most common on the head especially the scalp. The pilar cyst rate of growth is very slow; it takes several years to grow to a big size.

Epidemiology

Young individuals are more prone to developing trichilemmal cysts. Pilar cysts have no known racial predilection, and they occur more commonly in women than in men. Family history may be present since the disease follows autosomal dominant inheritance in some cases.

Pathophysiology

Pilar cysts are intradermal cysts that arise from the epithelium located between the sebaceous gland and the arrector pili muscle. They are lined by stratified squamous epithelium without a granular cell layer similar to what is seen in the outer root sheath of the hair follicle and filled with keratin and its breakdown products.

Histopathology

Pilar cysts are lined by thick capsules containing small layers of cuboidal, dark-staining basal epithelial cells in a palisade arrangement without an obvious intercellular gap. Those cells coalesce with multiple layers of keratinocytes forming squamous epithelium; these cells showed more maturation with dense eosinophilic-staining keratin in the absence of a granular cell layer. Sometimes we might see some areas of calcifications. Keratin in the pilar cysts stains with antikeratin antibodies similar to that seen in keratin derived from human hair. Trichilemmal cysts might rupture and of their components will leak into the dermis leading to the formation of foreign-body reaction. Rare malignant transformation in the form of increase mitotic figure along with cell atypia and necrosis might be seen in cases of proliferating trichilemmal cysts.

History and Physical

Pilar cysts are primarily diagnosed on clinical presentation. Most commonly, they are multiple lesions, but sometimes, single lesions might be seen. Pilar cysts usually occur in areas with dense hair follicle so that they are most commonly seen on the head especially the scalp, but they can also be found on the face, head, and neck. Trichilemmal cysts are usually asymptomatic unless they calcify or rupture their contents leading to inflammatory process and pain in the affected site. Sometimes, the presence of pilar cyst overpressure or bony prominence might lead to pain. Trichilemmal cysts usually present as flesh-colored, smooth, mobile, firm, and well-circumscribed nodules. Family history is very important since this condition can have an autosomal dominant pattern of inheritance. Usually, they are slow-growing nodules but sometimes they increase in size rapidly and it would indicates infection or malignant transformation. Young females are affected more than males.

Evaluation

Diagnosis of pilar cysts is mainly clinical, based on signs and symptoms and additional investigations rarely need to be done. Radiological studies sometimes are needed to exclude other differentials, especially with midline head and neck lesions and to check for the extent of the lesion and the involvement of the underlying central nervous system (CNS). CT scan is the best way to determine the extent of bone invasion. MRI can be used for more deeper soft tissue involvement and to visualize very tiny invasion.

Treatment / Management

The mainstay of treatment is radical surgical excision of the lesion including the wall of the cysts to avoid the recurrence. Then the content should be sent to the pathology department to confirm the diagnosis. Treatment is complete excision of the cyst. If the cysts return or become inflamed, then it is not recommended to remove surgically, and it is better to wait until the inflammation subsides to proceed to the option of surgical removal. Wound swab and culture sensitivity for the inflamed lesion is mandatory to exclude infection and to guide treatment options. Proliferating trichilemmal cysts might need need multiple surgical removal sessions along with radiation therapy and/ or chemotherapy.

Differential Diagnosis

  • Acne keloidalis nuchae
  • Cutaneous lipomas
  • Dermoid cyst
  • Epidermal inclusion cyst
  • Favre-Racouchot syndrome (nodular elastosis with cysts and comedones)
  • Pilomatrixoma
  • Steatocystoma multiplex

Treatment Planning

  1. Conservative treatment
  2. Surgical intervention in the form of complete surgical excision of the cyst with its sac to avoid recurrence
  3. Radiotherapy for select cases with malignant transformation
  4. Chemotherapy for rare malignant cases[1]

Prognosis

Generally, pilar cysts have good prognosis regardless of the presence of complications. Sequelae of trichilemmal cysts include inflammation, infection and malignant transformation (which is rare). Counseling is needed to assure the patient and his or her family since the disease is transmitted through the autosomal dominant way.[2]

Complications

A pilar cyst might cause pain especially over pressure areas; other complications include inflammation, cosmetic disfigurements, infection, and calcification. A complication from surgical removal may include bleeding, pain, infection, and scarring.[3]

Postoperative and Rehabilitation Care

After surgical removal of Pilar cyst, it is very important to taking care of the surgical site. Daily dressing is advisable along with normal saline and disinfectant solution, covering the sutures with gauze is recommended for the first very days. Typically, sutures should be removed in 7 to 10 days depending on the site of the cyst and status of the wound.[4]

Consultations

Pilar cyst is purely cutaneous condition and does not require consultations to any other specialties unless there is a comorbid disease or any additional complications.[5]

Pearls and Other Issues

Trichilemmal cysts are benign lesions, and they might transform into malignancy on rare occasions. Head and neck are the commonest sites to be affected. Recurrences and metastases have been observed. If the surgeon does not remove the sac completely, then the recurrence rate will be high. Merkel cell carcinoma sometimes might arise from pilar cysts.[6]

Enhancing Healthcare Team Outcomes

Assessment of any patients with Pilar cyst begins with members of a multidisciplinary team of nurses and physicians taking a thorough history and careful physical examination which is usually enough to reach the diagnosis in most of the cases. Rarely, biopsy of the lesion is needed for the diagnosis. Reassurance of the patient is very important. Patients who are interested in surgical treatment should be aware of the consequences of surgery since scar formation can be more disfiguring to the patient's image rather than the lesion itself.[7]


  • Image 5255 Not availableImage 5255 Not available
    Contributed by Daifallah M. Al Aboud, M.D.
Attributed To: Contributed by Daifallah M. Al Aboud, M.D.

Interested in Participating?

We are looking for contributors to author, edit, and peer review our vast library of review articles and multiple choice questions. In as little as 2-3 hours you can make a significant contribution to your specialty. In return for a small amount of your time, you will receive free access to all content and you will be published as an author or editor in eBooks, apps, online CME/CE activities, and an online Learning Management System for students, teachers, and program directors that allows access to review materials in over 500 specialties.

Improve Content - Become an Author or Editor

This is an academic project designed to provide inexpensive peer-reviewed Apps, eBooks, and very soon an online CME/CE system to help students identify weaknesses and improve knowledge. We would like you to consider being an author or editor. Please click here to learn more. Thank you for you for your interest, the StatPearls Publishing Editorial Team.

Pilar Cyst - Questions

Take a quiz of the questions on this article.

Take Quiz
All of the following are true regarding Pilar cysts EXCEPT:



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
All of the following statements are true regarding Pilar cysts EXCEPT:



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
Which of the following statements is true regarding trichilemmal cysts?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up

Pilar Cyst - References

References

Kucuk AI,Kocer B,Turan G,Gündüz Y,Özdemir K, A Benign Rare Lesion of the Breast: Giant Epidermal Inclusion Cyst. Cureus. 2018 May 18     [PubMed]
Ben Naftali Y,Shoufani A,Krausz J,Hershko D, Unusual presentation of epidermoid cyst mimicking breast cancer involving the areola-Case report. International journal of surgery case reports. 2018     [PubMed]
Palkó E,Póliska S,Sziklai I,Penyige A, Analysis of KRT1, KRT10, KRT19, TP53 and MMP9 expression in pediatric and adult cholesteatoma. PloS one. 2018     [PubMed]
Rossi E,Paganelli A,Mandel VD,Pellacani G, Plasma Exeresis Treatment for Epidermoid Cysts: A Minimal Scarring Technique. Dermatologic surgery : official publication for American Society for Dermatologic Surgery [et al.]. 2018 Jul 16     [PubMed]
Kaya G,Saurat JH, Cutaneous Adnexal Cysts Revisited: What We Know and What We Think We Know. Dermatopathology (Basel, Switzerland). 2018 Apr-Jun     [PubMed]
Uyanikoglu H,Hilali NG,Yardimciel M,Koyuncu I, A new biomarker for the early diagnosis of ovarian torsion: SCUBE-1. Clinical and experimental reproductive medicine. 2018 Jun     [PubMed]
Lee KC,Chang YW,Chen CP, Axillary web syndrome following epidermal inclusion cyst: a case report and literature review. Clinical and experimental dermatology. 2018 Jun 7     [PubMed]

Disclaimer

The intent of StatPearls is to provide practice questions and explanations to assist you in identifying and resolving knowledge deficits. These questions and explanations are not intended to be a source of the knowledge base of all of medicine, nor is it intended to be a board or certification review of Dermatology. The authors or editors do not warrant the information is complete or accurate. The reader is encouraged to verify each answer and explanation in several references. All drug indications and dosages should be verified before administration.

StatPearls offers the most comprehensive database of free multiple-choice questions with explanations and short review chapters ever developed. This system helps physicians, medical students, dentists, nurses, pharmacists, and allied health professionals identify education deficits and learn new concepts. StatPearls is not a board or certification review system for Dermatology, it is a learning system that you can use to help improve your knowledge base of medicine for life-long learning. StatPearls will help you identify your weaknesses so that when you are ready to study for a board or certification exam in Dermatology, you will already be prepared.

Our content is updated continuously through a multi-step peer review process that will help you be prepared and review for a thorough knowledge of Dermatology. When it is time for the Dermatology board and certification exam, you will already be ready. Besides online study quizzes, we also publish our peer-reviewed content in eBooks and mobile Apps. We also offer inexpensive CME/CE, so our content can be used to attain education credits while you study Dermatology.